What was the valve spring rate supposed to be and what do they actually
measure now? That should resolve any question of whether the springs
weakened over time.
Regards, Neil Tucson, AZ
-----Original Message-----
From: Bill Pokey Bennett [mailto:bennevl@bellsouth.net]
Sent: Wednesday, February 19, 2003 8:06 PM
To: Landspeed List; Keith Turk
Subject: Mule Motor Autopsy
Ok I forwarded the information to someone that has lots of expierence
runnning valvetrain dynamic test at our r&d test center. Seems like lifter
to lobe seperation took place destroying lifters. Then the destroyed lifter
took out camshaft which took out rod. One thing you have to understand is
how this motor was run. Probably one of the harshes ways to run a motor
worse than any dyno run could do. I think on this run the rev limiter was
some where around 6500 or 6700 rpm. Forgive me Keith if I am wrong. Now this
is a very radical hydraulic cam. First time driver in the car so I suspect
it was held at a high steady state rpm for long period due to the fact of
speed limit on pass. Imagine trying not to go over 125 yet the car has the
potential to go well beyond this at about 3/4 mile. So for the last 1/4 mile
the motor was not accelerating. There might have been 15 or 20 runs on the
springs which were 2 seasons old. I don't know if the rockers were backed
off between the 2 seasons it was run. Weaken springs, high steady state rpm
and Shazam 3 piece cam and rod out both side of block.
Bill
----- Original Message -----
From: "Jerry Davis" <jerry.davis@arcnc.com>
To: "'Bill Pokey Bennett '" <bennevl@bellsouth.net>
Sent: Wednesday, February 19, 2003 8:46 PM
Subject: RE: Motor Autopsy
> The lifters broke due to separation..massive contact loads and stresses
> when the valve lifter launches off the nose of the cam (agressive valve
> opening acceleration and velocity). If there were any broken valve
springs,
> it's pretty definate that there was separation. It's an awesome thing to
> see. The valve spring can be over stressed and start to weaken with only
> minimal separation. I've seen only one broken cam due to this, but I've
seen
> countless lifters destroyed (hydraulic lifters, not solid).
> JD
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